How to debug Systemd problems

From FedoraProject

If you are experiencing a problem with system boot up due to Systemd, please see the common bugs document before filing a bug. Some easy configuration tweaks that fix a wide range of issues may be listed there. If the problem you are seeing is not listed there or none of the workarounds seem to help, please consider filing a bug to help us make Fedora run better on your hardware.

Be prepared to include some information (logs) about your system as well. These should be complete (no snippets please), not in an archive, uncompressed, with MIME type set as text/plain.

Various useful systemd related commands

Run systemctl list-jobs

To identify slow boot and look for the jobs that are "running" those jobs are the ones where boot waits for completion on and the ones that listed as "waiting" will be executed only after those which are "running" are completed.

Run systemctl show -p "Wants" multi-user.target

To figure out which services a target like multi-user.target pulls in.

Run systemd --test

Run {{{1}}}

To examine what gets started when when booted into a specific target. ( In the above example the multi-user.target )

Additional systemd boot parameters

The following boot parameters are also available to further assist with debugging boot issues.

systemd.unit=

Overrides the unit to activate on boot. This may be used to temporarily boot into a different boot unit, for example rescue.target or emergency.service. ( Defaults to default.target. )

systemd.dump_core=

Takes a boolean argument. If true systemd dumps core when it crashes. Otherwise no core dump is created. ( Defaults to true )

systemd.crash_shell=

Takes a boolean argument. If true systemd spawns a shell when it crashes. Otherwise no core dump is created. Defaults to false, for security reasons, as the shell is not protected by any password authentication.

systemd.crash_chvt=

Takes an integer argument. If positive systemd activates the specified virtual terminal when it crashes. ( Defaults to -1 )

Takes a boolean argument. If true shows terse service status updates on the console during bootup. ( Defaults to true )

systemd.sysv_console=

Takes a boolean argument. If true output of SysV init scripts will be directed to the console. ( Defaults to true, unless quiet is passed as kernel command line option in which case it defaults to false. )

systemd.log_target=

Set log target. Argument must be one of console, syslog, kmsg, syslog-or-kmsg, null.